import java.util.Scanner;

public class Java005 {
    public static void main(String[] args) {
        String level;
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入成绩");
        int grade = sc.nextInt();
//        System.out.println(judgment(grade));
        level = grade>=90?"A":(grade>=60?"B":"C");
        System.out.println(level);


    }
    public static String judgment(int grade){
        if(grade>100 &&grade<0){
            return "请输入有效成绩";
        } else if(grade>=90){
            return "A";
        }else if(grade>=60){
            return "B";
        }else{
            return "C";
        }
    }
}
